I won't ever order like that again. USPS is great but once it hits SA shores... you're lucky if you ever get what you paid for.
Rather use Aramex Global Shopper. They ship to an address in Hong Kong, USA, UK, etc and then ship to ZA. Full tracking, etc.
I mean to each his own but I haven't trusted SAPO since their last few strikes about 4 years ago. So much damage and lost parcels. And I've never received 2-4 parcels sent from the US via USPS coz it's locally handled by SAPO.
But that doesn't help you right now. For your current situation... you can expect to wait as much as 3 months. You normally have to get a local tracking number once it hits ZA. So you phone SAPO with your USPS tracking number and they give you the local one. Then hound them at least weekly.
Good luck and let us know how it goes, bud.